I have a very different take on this. Since humans started noticing the days begin getting longer right around this time of the year, there have been midwinter festivals, a time of feasting and sharing of gifts. I think it is deep in our human social DNA to want to celebrate this time of the year. Christianity co-opted existing winter festivals-- I think most scholars agree that Jesus' birthday was not December 25 (Kris Kristofferson not withstanding, I can't see Jesus as a Capricorn).
It would be a real relief if we could just admit that there are two holidays: Christmas as social/cultural phenomenon that harkens back to our early human roots, albeit on hyperdrive and Christmas/Advent as a time of spiritual reflection.
If Jesus was truly the reason for the season, then Easter would be a much bigger holiday than it is now.
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